I'm using FontForge to develop a sans serif Postscript font. I've encountered an unusual problem with the rendering of a hinted "b."

I've attached the pfb and afm files for MySans-Regular to this email. The file contains the b glyph, and an o for comparison. If you view the b and o using FreeType's ftview program at size 20, then the inside of the counter of the b is 5 pixels wide. However, at size 21, the counter is only 4 pixels wide. This looks very strange. The o seems to work as expected. If I remove the right vertical hint from the bowl, the width seems right in ftview, but the bowl is fuzzy. I've also noticed a problem with d, q, g, and p being too narrow, as well as h and n.

Is there a problem with the hinting? Or is my font not constructed correctly?

I've also included a picture of this phenomenon in ftview. I'm using freetype-2.1.9-2 on Fedora Core 4 with xorg-x11-6.8.2-37.FC4.49.2_4.rhfc4.at.